Factor out flutter manifest logic (#12237)

diff --git a/packages/flutter_tools/test/flutter_manifest_test.dart b/packages/flutter_tools/test/flutter_manifest_test.dart
new file mode 100644
index 0000000..2395172
--- /dev/null
+++ b/packages/flutter_tools/test/flutter_manifest_test.dart
@@ -0,0 +1,336 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_tools/src/cache.dart';
+import 'package:flutter_tools/src/flutter_manifest.dart';
+
+import 'package:test/test.dart';
+
+import 'src/common.dart';
+import 'src/context.dart';
+
+void main() {
+  setUpAll(() {
+    Cache.flutterRoot = getFlutterRoot();
+  });
+
+  group('FlutterManifest', () {
+    test('has no fonts or assets when the "flutter" section is empty', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+      expect(flutterManifest, isNotNull);
+      expect(flutterManifest.appName, 'test');
+      expect(flutterManifest.usesMaterialDesign, false);
+      expect(flutterManifest.fontsDescriptor, isEmpty);
+      expect(flutterManifest.fonts, isEmpty);
+      expect(flutterManifest.assets, isEmpty);
+    });
+
+    test('knows if material design is used', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+flutter:
+  uses-material-design: true
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+      expect(flutterManifest.usesMaterialDesign, true);
+    });
+
+    test('has two assets', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+flutter:
+  uses-material-design: true
+  assets:
+    - a/foo
+    - a/bar
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+      expect(flutterManifest.assets, <String>['a/foo', 'a/bar']);
+    });
+
+    test('has one font family with one asset', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+flutter:
+  uses-material-design: true
+  fonts:
+    - family: foo
+      fonts:
+        - asset: a/bar
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+
+      expect(flutterManifest.fontsDescriptor.toString(), '[{fonts: [{asset: a/bar}], family: foo}]');
+      final List<Font> fonts = flutterManifest.fonts;
+      expect(fonts.length, 1);
+      final Font font = fonts[0];
+      final String fontDescriptor = '{family: foo, fonts: [{asset: a/bar}]}';
+      expect(font.descriptor.toString(), fontDescriptor);
+      expect(font.familyName, 'foo');
+      final List<FontAsset> assets = font.fontAssets;
+      expect(assets.length, 1);
+      final FontAsset fontAsset = assets[0];
+      expect(fontAsset.asset, 'a/bar');
+      expect(fontAsset.weight, isNull);
+      expect(fontAsset.style, isNull);
+    });
+
+    test('has one font family with a simple asset and one with weight', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+flutter:
+  uses-material-design: true
+  fonts:
+    - family: foo
+      fonts:
+        - asset: a/bar
+        - asset: a/bar
+          weight: 400
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+
+      final String expectedFontsDescriptor = '[{fonts: [{asset: a/bar}, {weight: 400, asset: a/bar}], family: foo}]';
+      expect(flutterManifest.fontsDescriptor.toString(), expectedFontsDescriptor);
+      final List<Font> fonts = flutterManifest.fonts;
+      expect(fonts.length, 1);
+      final Font font = fonts[0];
+      final String fontDescriptor = '{family: foo, fonts: [{asset: a/bar}, {weight: 400, asset: a/bar}]}';
+      expect(font.descriptor.toString(), fontDescriptor);
+      expect(font.familyName, 'foo');
+      final List<FontAsset> assets = font.fontAssets;
+      expect(assets.length, 2);
+      final FontAsset fontAsset0 = assets[0];
+      expect(fontAsset0.asset, 'a/bar');
+      expect(fontAsset0.weight, isNull);
+      expect(fontAsset0.style, isNull);
+      final FontAsset fontAsset1 = assets[1];
+      expect(fontAsset1.asset, 'a/bar');
+      expect(fontAsset1.weight, 400);
+      expect(fontAsset1.style, isNull);
+    });
+
+    test('has one font family with a simple asset and one with weight and style', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+flutter:
+  uses-material-design: true
+  fonts:
+    - family: foo
+      fonts:
+        - asset: a/bar
+        - asset: a/bar
+          weight: 400
+          style: italic
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+
+      final String expectedFontsDescriptor = '[{fonts: [{asset: a/bar}, {style: italic, weight: 400, asset: a/bar}], family: foo}]';
+      expect(flutterManifest.fontsDescriptor.toString(), expectedFontsDescriptor);
+      final List<Font> fonts = flutterManifest.fonts;
+      expect(fonts.length, 1);
+      final Font font = fonts[0];
+      final String fontDescriptor = '{family: foo, fonts: [{asset: a/bar}, {weight: 400, style: italic, asset: a/bar}]}';
+      expect(font.descriptor.toString(), fontDescriptor);
+      expect(font.familyName, 'foo');
+      final List<FontAsset> assets = font.fontAssets;
+      expect(assets.length, 2);
+      final FontAsset fontAsset0 = assets[0];
+      expect(fontAsset0.asset, 'a/bar');
+      expect(fontAsset0.weight, isNull);
+      expect(fontAsset0.style, isNull);
+      final FontAsset fontAsset1 = assets[1];
+      expect(fontAsset1.asset, 'a/bar');
+      expect(fontAsset1.weight, 400);
+      expect(fontAsset1.style, 'italic');
+    });
+
+    test('has two font families, each with one simple asset and one with weight and style', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+flutter:
+  uses-material-design: true
+  fonts:
+    - family: foo
+      fonts:
+        - asset: a/bar
+        - asset: a/bar
+          weight: 400
+          style: italic
+    - family: bar
+      fonts:
+        - asset: a/baz
+        - weight: 400
+          asset: a/baz
+          style: italic
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+
+      final String expectedFontsDescriptor = '[{fonts: [{asset: a/bar}, {style: italic, weight: 400, asset: a/bar}], family: foo},'
+                                             ' {fonts: [{asset: a/baz}, {style: italic, weight: 400, asset: a/baz}], family: bar}]';
+      expect(flutterManifest.fontsDescriptor.toString(), expectedFontsDescriptor);
+      final List<Font> fonts = flutterManifest.fonts;
+      expect(fonts.length, 2);
+
+      final Font fooFont = fonts[0];
+      final String barFontDescriptor = '{family: foo, fonts: [{asset: a/bar}, {weight: 400, style: italic, asset: a/bar}]}';
+      expect(fooFont.descriptor.toString(), barFontDescriptor);
+      expect(fooFont.familyName, 'foo');
+      final List<FontAsset> fooAassets = fooFont.fontAssets;
+      expect(fooAassets.length, 2);
+      final FontAsset fooFontAsset0 = fooAassets[0];
+      expect(fooFontAsset0.asset, 'a/bar');
+      expect(fooFontAsset0.weight, isNull);
+      expect(fooFontAsset0.style, isNull);
+      final FontAsset fooFontAsset1 = fooAassets[1];
+      expect(fooFontAsset1.asset, 'a/bar');
+      expect(fooFontAsset1.weight, 400);
+      expect(fooFontAsset1.style, 'italic');
+
+      final Font barFont = fonts[1];
+      final String fontDescriptor = '{family: bar, fonts: [{asset: a/baz}, {weight: 400, style: italic, asset: a/baz}]}';
+      expect(barFont.descriptor.toString(), fontDescriptor);
+      expect(barFont.familyName, 'bar');
+      final List<FontAsset> barAssets = barFont.fontAssets;
+      expect(barAssets.length, 2);
+      final FontAsset barFontAsset0 = barAssets[0];
+      expect(barFontAsset0.asset, 'a/baz');
+      expect(barFontAsset0.weight, isNull);
+      expect(barFontAsset0.style, isNull);
+      final FontAsset barFontAsset1 = barAssets[1];
+      expect(barFontAsset1.asset, 'a/baz');
+      expect(barFontAsset1.weight, 400);
+      expect(barFontAsset1.style, 'italic');
+    });
+
+    testUsingContext('has only one of two font familes when one declaration is missing the "family" option', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+flutter:
+  uses-material-design: true
+  fonts:
+    - family: foo
+      fonts:
+        - asset: a/bar
+        - asset: a/bar
+          weight: 400
+          style: italic
+    - fonts:
+        - asset: a/baz
+        - asset: a/baz
+          weight: 400
+          style: italic
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+
+
+      final String expectedFontsDescriptor = '[{fonts: [{asset: a/bar}, {style: italic, weight: 400, asset: a/bar}], family: foo},'
+                                             ' {fonts: [{asset: a/baz}, {style: italic, weight: 400, asset: a/baz}]}]';
+      expect(flutterManifest.fontsDescriptor.toString(), expectedFontsDescriptor);
+      final List<Font> fonts = flutterManifest.fonts;
+      expect(fonts.length, 1);
+      final Font fooFont = fonts[0];
+      final String barFontDescriptor = '{family: foo, fonts: [{asset: a/bar}, {weight: 400, style: italic, asset: a/bar}]}';
+      expect(fooFont.descriptor.toString(), barFontDescriptor);
+      expect(fooFont.familyName, 'foo');
+      final List<FontAsset> fooAassets = fooFont.fontAssets;
+      expect(fooAassets.length, 2);
+      final FontAsset fooFontAsset0 = fooAassets[0];
+      expect(fooFontAsset0.asset, 'a/bar');
+      expect(fooFontAsset0.weight, isNull);
+      expect(fooFontAsset0.style, isNull);
+      final FontAsset fooFontAsset1 = fooAassets[1];
+      expect(fooFontAsset1.asset, 'a/bar');
+      expect(fooFontAsset1.weight, 400);
+      expect(fooFontAsset1.style, 'italic');
+    });
+
+    testUsingContext('has only one of two font familes when one declaration is missing the "fonts" option', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+flutter:
+  uses-material-design: true
+  fonts:
+    - family: foo
+      fonts:
+        - asset: a/bar
+        - asset: a/bar
+          weight: 400
+          style: italic
+    - family: bar
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+
+      final String expectedFontsDescriptor = '[{fonts: [{asset: a/bar}, {style: italic, weight: 400, asset: a/bar}], family: foo},'
+                                             ' {family: bar}]';
+      expect(flutterManifest.fontsDescriptor.toString(), expectedFontsDescriptor);
+      final List<Font> fonts = flutterManifest.fonts;
+      expect(fonts.length, 1);
+      final Font fooFont = fonts[0];
+      final String barFontDescriptor = '{family: foo, fonts: [{asset: a/bar}, {weight: 400, style: italic, asset: a/bar}]}';
+      expect(fooFont.descriptor.toString(), barFontDescriptor);
+      expect(fooFont.familyName, 'foo');
+      final List<FontAsset> fooAassets = fooFont.fontAssets;
+      expect(fooAassets.length, 2);
+      final FontAsset fooFontAsset0 = fooAassets[0];
+      expect(fooFontAsset0.asset, 'a/bar');
+      expect(fooFontAsset0.weight, isNull);
+      expect(fooFontAsset0.style, isNull);
+      final FontAsset fooFontAsset1 = fooAassets[1];
+      expect(fooFontAsset1.asset, 'a/bar');
+      expect(fooFontAsset1.weight, 400);
+      expect(fooFontAsset1.style, 'italic');
+    });
+
+    testUsingContext('has no font family when declaration is missing the "asset" option', () async {
+      final String manifest = '''
+name: test
+dependencies:
+  flutter:
+    sdk: flutter
+flutter:
+  uses-material-design: true
+  fonts:
+    - family: foo
+      fonts:
+        - weight: 400
+''';
+      final FlutterManifest flutterManifest = await FlutterManifest.createFromString(manifest);
+
+      final String expectedFontsDescriptor = '[{fonts: [{weight: 400}], family: foo}]';
+      expect(flutterManifest.fontsDescriptor.toString(), expectedFontsDescriptor);
+      final List<Font> fonts = flutterManifest.fonts;
+      expect(fonts.length, 0);
+    });
+  });
+}